The primary aims of the project are as follows: 1. To evaluate the magnitude of the problem of metronidazole resistance in trichomoniasis. Unselected isolates from 3 sexually transmitted disease clinics in Baltimore will be screened in vitro for drug resistance as will 150 isolates on hand. 2. To determine whether or not minimal dosage and duration of metronidazole therapy necessary for drug resistant trichomoniasis can be predicted by in vitro resistance assays. Strains sent us for evaluation of drug resistance and isolates from patients treated by us will provide the basis for attempts to relate the MLC in vitro to effective therapeutic regimens. Drug sensitivity assays are provided by us for strains clinically refractory to metronidazole with the proviso that results of therapy be made available to us for the above purpose. 3. To continue studies on properties of trichomonads which may lead to additional therapeutic adjuncts. Ascorbic acid and methenamine mandelate were employed by us (1) in the treatment of drug resistant trichomoniasis based solely upon in vitro studies (2); we have on data, however to indicate their therapeutic efficacy in vivo. The role of ascorbic acid in drug resistant trichomoniasis will be approached by a mouse model, but no animal model suitable for evaluating methenamine is currently available. A new approach will be based on data on hand showing inhibitory and lethal effects of certain hexosamines and stereoisomers of glucose. 4. To cooperate with Centers for Disease Control, Atlants, Ga. in establishing surveillance of patients with drug resistant trichomoniasis who have received relatively large doses of metronidazole, and to collaborate in investigations of isoenzyme patterns of drug resistant and susceptible trichomonads.